Method of annealing metal



Aug. 28, $1923. 1,466.57

R. E. TALLEY METHOD OF ANNEALING METALS Filed June 9, 1919 WITNESSES: INVENTOR Arrb citizen of the United States, and a resident of Irwin, in the county of Alleghenyfand Patented Aug. 28, 1923.

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RANDAL E. TALLEY, OF IRWIN, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PEN1\T SYLVANIA.

METHOD OF ANNEAIJNG METAL.

Application filed June 9,

r 1 7 lo al, whom 115 may ('07'607'12 Be it known that I, RANDAL E. TALLEY, a

State of Pennsylvania, have invented anew and useful Improvement in Methods ofAn-' nealing Metals, of which the following is a purpose which comprises a furnace body 1,

Specification.

My invention relates to-a method-of annealing metals, more particularly -aluminum, and it has for'its primary object the provision of a method which will insure better and more uni-form results'than any meth-' ods previously employed and known to me.-

Heret0fore,to the best of my knowledge, aluminum, in sheet or other forms, has been stacked in a large annealing furnace, oftentimes exceeding 30 feet 1n length, the an-- nealing furnace has bee'n sealed, and a fire has been started to heat the furnace and keep it heated at the're'quired temperature for a long period oftime, ranging from 24 to 48 hours, in most instances.

The old method of annealing aluminum has been very unsatisfactory because of nonuniformity of results. The large stacks of aluminum do not heat evenly, the outer portions being highly heated before the inner portions become appreciably heated, with the result that the central portions of the sheets, or other forms being annealed, are hard.

Another fundamental objection to this method of annealing aluminum is that the furnaces are usually heated by means of oil or gas flames and the products of combustion of such fuels combine with, or penetrate, the aluminum to such extent as to produce blisters on the surface of the metal being annealed. Porosity may also be caused thereby.

One of the objects of my present invention resides in providing a. methodof annealing aluminum by which the heating may be constant and, consequently, the physical properties of the aluminum may be kept uniform and all blistering may be prevented.

A still further object of my invention resides in providing a method of heat treatment which will not introduce impurities into the metal being annealed.

In order to insure a clear and accurate understanding of my present method, reference may be had to the drawings illustrating one form of apparatus suitable for prac" 1919. Serial N0. 302,837.

tising my invention. In the drawings, Fig, i 1 1s a sectional plan View of an electric furnace, and Fig. 2 is a vertical sectional view thereof.

While various types of electric furnaces lmay be employed with equal facility, I have illustrated one particularly adapted to the aluminum sheets being annealed. A second inclined roller-table 5 may be disposed to receive the material as it passes from the furnace and to deposit it 'upon a cooling conveyer 6, of any desired character.

In practising my invention, the aluminum to be annealed, which is preferably in the form of thin sheets, is supplied to the table 3 and fed by it to the conveyer 4 which is driven at a predetermined speed. The electric furnace is maintained at a constant temperature, suitable for the proper annealing of the aluminum, which may be' between 350 C. to 500 C1 By this means, the alumimum is brought to the desired temperatureafter which it passes from the furnace to the cooling conveyer 6 where it may cool naturally in the air or may be artifically cooled, as preferred.

My invention depends principally upon the fact that aluminum may be successfully annealed by heating it to a certain definite temperature, such as 400 (1, and that. it ne d not be kept at this temperature for any considerable length of time. It is, therefore, possible to anneal the aluminum during its brief passage through an electrically heated furnace, as above described.

The time required to properly anneal the aluminum will, of course, depend upon the form of the material but tests made by me indicate that thin sheets ofapproximately 0.04 inch in thickness may be annealedin ten minutes or less. It will, therefore, be obvious that there is a great saving of time hy iny process, with a consequent quick turn-over of material resulting in a saving of storage space. Furthermore, my method permits continuous annealing of th aluminum and, consequently, insures an uninterrupted supply of the annealed material.

As the heat of the electric. furnace may be readily and accurately regulated and as only small quantities of the metal are in the furnace at any one time. great uniformity is insured, and the physical properties of the annealed metal are far superior to those of metal annealed by old methods.

There is no tendency of the metal to blister during its annealing in the electric furnace and, as the electric heat insures an inert atmosphere, there is no absorption of gases or other impurities.

Preferably the aluminum will be supplied to the furnace in single sheets although several sheets may be stacked upon each other if desired. 'For'this reason, the heating elements of the furnace may be disposed only a fraction of an inch above the surface of the c'ofli'ever so that the volume of the heating chamber bf the furnace is reduced to, in some instances, as loiv as one per cent of that of the furnaces now employed. This naturally results in a great saving of heat Wlth particular reference to the annealing; of aluminum, it will be appreciated that it may be employed for annealing other metals, if found suited for the purpose. It will also be umlerstood that any suitable type oi electric furnace and of conveyer structures may be employed. For these reasons, no limitations are to be imposed upon my invention other than those indicated in the claims.

I claim as my invention:

1. A method of annealing aluminum which comprises passing the aluminum through an electrically heated furnace at a predetermined speed.

2. A method of annealing galuminum which comprises continuously passing successive pieces of aluminum. at a predetermined rate, through an electric furnace heatcd to a predetermined degree.

aluminum in small quantities to an elec-' t-rically heated furnace, causing the aluminum so supplied to pass continuously through the furnace at a predetermined rate of speed, and cooling the aluminum as it passes from the furnace.

In testimony whereof; I have hereunto subscribed my name this 31st day of May,

RAN DAL E. TALLEY. 

